Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

respiratory physiology > control of respiration 2/chemical control of respiration (R7) > Flashcards

control of respiration 2/chemical control of respiration (R7) Flashcards

1
Q

homeostasis

A
  • stable internal environment
  • essential for normal cell and body function
  • body systems maintain homeostasis, which is essential for survival of cells that make up body systems which maintain homeostasis…
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

components of our bodies internal environment that must be maintained within narrow ranges

A
  • concentration of water and electrolytes within and outside the cells
  • pressures and volumes
  • pH
  • body temperature
  • concentration of nutrients eg.glucose
  • concentration of O2 and CO2
  • concentration of waste products eg. urea
  • > pH, and concentration of O2 and CO2 are examples of negative feedback systems
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

negative feedback systems

A
  • primary type of homeostatic control system

- opposes initial change

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

examples of negative feedback system

A
  • control of gases (O2 and CO2)

- control of pH (H+)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

components of negative feedback system

A
  • sensor (monitors magnitude of a controlled variable)
  • control center (compares sensor’s input with a set point)
  • effector/s (makes a response to produce a desired effect)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

cycle/steps involved in negative feedback system

A

deviation in controlled variable -> detected by sensor -> which informs control center -> which sends instructions to effector (s) -> which brings about a compensatory response -> which results in restoration of controlled variable to normal -> this relieves the deviation in controlled variable and also leads to negative feedback to shut off the system responsible for the response

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

chemical control of respiration

A
  • example of a negative feedback control system
  • the controlled variables are the blood gas tensions, especially carbon dioxide
  • chemoreceptors sense the values of the gas tensions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

chemoreceptors

A

sense the values of the gas tensions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

peripheral chemoreceptors

A
  • situated in the carotid bodies and aortic bodies

- sense tension of oxygen, carbon dioxide and [H+] (H+ concentration) in the blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

central chemoreceptors

A
  • situated near the surface of the medulla of the brainstem

- respond to the [H+] (H+ concentration) of the cerebrospinal fluid (CSF)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

CSF

A
  • cerebrospinal fluid
  • separated from the blood by the blood-brain barrier
  • relatively impermeable to H+ and bicarbonate
  • CO2 diffuses readily
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

why is CSF less buffered than blood

A
  • CSF contains less protein than blood therefore is less buffered than blood
  • protein hemoglobin makes an excellent buffer, it can bind to small amounts of acid in the blood, helping to remove that acid before it changes the blood’s pH
  • > protein binds to CO2 generated H+
  • therefore because there is less Hb in CSF, then less excess H+ are binded and removed so the pH remains more acidic than returning to neutral
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

hypercapnia

A

increased arterial PCO2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

hypercapnia (increased arterial PCO2) and ventilation

A
  • the ventilation system is very responsive to PCO2 (due to the central chemoreceptors responding to levels of CO2 generated H+)
  • as PCO2 increases, ventilation increases
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

controlled variables in chemical control of respiration (eg. of negative feedback system)

A
  • decreased PO2
  • increased arterial PCO2
  • increased arterial [H+]
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

sensor in chemical control of respiration (eg. of negative feedback system)

A

chemoreceptors (peripheral and central)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

control center in chemical control of respiration (eg. of negative feedback system)

A

respiratory centers

18
Q

effector (s) in chemical control of respiration (eg. of negative feedback system)

A

respiratory muscles leading to changes in ventilation

19
Q

hypoxic drive of ventilation

A
  • the effect is all via the peripheral chemoreceptors (This response does not control ventilation rate at normal pO2, but below normal the activity of neurons innervating these receptors increases dramatically, so much so to override the signals from central chemoreceptors in the hypothalamus, increasing pO2 despite a falling pCO2)
  • stimulated only when arterial PO2 falls to low levels (
20
Q

hypoxia

A

decreased arterial PO2

21
Q

hypoxia (decreased arterial PO2) and ventilation

A

-peripheral chemoreceptors are stimulated when PO2 falls to low levels (

22
Q

what is hypoxia at high altitudes caused by

A

decreased partial pressure of inspired oxygen (PiO2)

23
Q

PiO2

A

partial pressure of inspired O2

24
Q

what is the acute response to hypoxia at high altitudes

A
  • hyperventilation

- and increased cardiac output

25
Q

what are the symptoms of acute mountain sickness (due to hypoxia at high altitudes)

A
  • headache
  • fatigue
  • nausea
  • tachycardia
  • dizziness
  • sleep disturbance
  • exhaustion
  • shortness of breath
  • unconsciousness
26
Q

PAO2 (alveolar gas equation)

A
  • partial pressure of oxygen in the alveolar air
  • PAO2= PiO2 - [PaCO2/0.8]
  • PAO2= 150 - [40/0.8]
  • PAO2=150-50 = 100mHg (13.3 kPa) at sea level
27
Q

PiO2

A

=partial pressure of O2 in inspired air

  • as the air in the respiratory tract is saturated with water, the water vapour pressure contributes about 47mmHg to the total pressure in the lungs
  • therefore the pressure of inspired air = atmospheric pressure - water vapour pressure (760 - 47 = 713 mmHg at sea level)
  • PiO2 would then = 713 x 0.21 = 150mmHg
28
Q

PaCO2

A

partial pressure of CO2 in arterial blood

29
Q

respiratory exchange ratio (RER)

A

=0.8

-ratio of CO2 produced/O2 consumed for someone eating a mixed diet

30
Q

normal arterial PCO2

A

40mmHg

31
Q

how would you use the alveolar gas equation to calculate the partial pressure of oxygen in alveolar air (PAO2) at the top of mount Everest for example

A
  • you would have to be given the PiO2 (partial pressure of O2 in inspired air) and substitute it into the equation (PAO2= PiO2 - [PaCO2/0.8])
  • PiO2 at the top of mount Everest = 43mmHg
32
Q

PiO2 at sea level

A

150mmHg

33
Q

chronic adaptations to high altitudes hypoxia

A
  • increased RBC production (polycythaemia) which increases the O2 carrying capacity of blood
  • increased 2,3 BPG produced within RBC which increases the ease at which O2 is offloaded into tissues
  • increased number of capillaries which increases the ease at which blood diffuses
  • increased number of mitochondria which means that O2 can be used more efficiently
  • kidneys conserve acid which decreases the arterial pH causing an increased release of O2 (bohr effect)
34
Q

H+ drive of respiration

A
  • the effect is via the peripheral chemoreceptors
  • H+ doesn’t readily cross the brain barrier (CO2 does)
  • the peripheral chemoreceptors play a major role in adjusting for acidosis caused by the addition of non-carbonic H+ to the blood (eg.lactic acid during exercise; and diabetic ketoacidosis)
  • their stimulation by H+ causes hyperventilation increases elimination of CO2 from the body (remember CO2 can generate H+ so its increase elimination helps reduce the load of H+ in the body)
  • this is important in acid-base balance
35
Q

acidosis

A

an excessively acid condition of the body fluids or tissues

36
Q

neural and chemical factors that may increase ventilation during exercise

A
  • reflexes originating from body movement
  • adrenaline release
  • impulses from the cerebral cortex
  • increase in body temperature
  • later: accumulation of CO2 and H+ generated by active muscles
37
Q

effect of decreased PO2 in the arterial blood on the peripheral chemoreceptors

A

-stimulates only when the arterial PO2 has fallen to the point of being life threatening (

38
Q

effect of decreased PO2 in the arterial blood on the central chemoreceptors

A

-directly depresses the central chemoreceptors and the respiratory center itself when

39
Q

effect of increased PCO2 in the arterial blood and increased H+ in the brain ECF on the peripheral chemoreceptors

A

weakly stimulates

40
Q

effect of increased PCO2 in the arterial blood and increased H+ in the brain ECF on the central chemoreceptors

A
  • strongly stimulates, is the dominant control of respiration
  • levels >70-80mmHg directly depress the respiratory center and the central chemoreceptors
41
Q

effect of increased H+ in the arterial blood on the peripheral chemoreceptors

A
  • stimulates

- important in acid-base balance

42
Q

effect of increased H+ in the arterial blood on the central chemoreceptors

A
  • does not affect

- cannot penetrate the blood-brain barrier

respiratory physiology (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions